raw data format in the daq
DESCRIPTION
Raw Data Format in the DAQ. Franco CARENA CERN PH-AID ALICE Offline October 2006. Raw data formatting in the DAQ. CTP. Event Fragment over DDL (CDH + Raw Data). LTU. LTU. TTC. TTC. Event Fragment in LDC (Eq Header + CDH + Raw Data). FERO. FERO. FERO. FERO. DDL. - PowerPoint PPT PresentationTRANSCRIPT
Raw Data Formatin the DAQ
Franco CARENACERN PH-AID
ALICE OfflineOctober 2006
DATE V5 2Data Format
Raw data formatting in the DAQ
GDC GDC
CTP
LTU
FERO FERO
LDC
Event Building Network
Event Fragmentover DDL
(CDH + Raw Data)
DDL
Sub-event to network or to
disk(Header + 1 or several event fragments)
Event(Header + 1 or
several sub-events)
LDC
DDL
FERO FERO
LTU
TTC TTC
Event Fragment in LDC
(Eq Header + CDH + Raw Data)
Data file(DATE or ROOT
format) ALICE Standard data format is ROOT !
DATE V5 3Data Format
Event Logic Structure
Base Header
Sub-event
(Header extension)
Event Fragment
Event Fragment
LDC
Equipment HeaderEvent fragment
Raw data
DDL
GDC
Sub-event
Sub-event
Sub-event
Sub-event
Base Header
Event
(Header extension)
Equipment Header
Common Data Header
DATE V5 4Data Format
Common Data Header
CDH Format
The Common Data Header (CDH) needs to be generated by the detector electronics together with the Trigger System and transmitted over the DDL (first 8 words of each fragment).
“Data Format over the ALICE DDL”, ALICE-INT-2002-010 V10.0
Block Length
Bunch Crossing0L1 Trigger MessageVersion
0
0
1
2
3
Orbit Number
Block Attributes Participating Sub-Detectors
4
5
6
0 Mini Event IDStatus&Error Bits
Trigger Classes Low
ROI Low 0 Trigger Classes High
ROI High7
31 24 16 8 0
MandatoryOptionalMust be zero
Version = 2 ! 0
DATE V5 5Data Format
Equipment Header(28 bytes)
equipment sizeequipment type
equipment id
type attribute
basic element size
+0
+8
+4
+12
+24
equipment header + fragment size
equipment type (RORC)equipment id
DetectorIdentifier
DDL Index
DATE V5 6Data Format
DDL Index (Detector Dep.)
DDL Links identifiers (Side A)
DATE V5 7Data Format
LDC/GDC Headerevent size
event magicevent header size
event version
+0
+8
+4
+12
event typeevent run number
+16
+20
event id
event trigger pattern
event detectors pattern
type attribute
event LDC idevent GDC id
+24
+32
+40
+44
+56
+60
eventTimestamp+64
total size in bytes
68 bytes + extension
period + orbit + bunch crossing
derived from the L2a message
derived from the L2a message
flags
time()
DATE V5 8Data Format
Event Format
LDC
LDC
GDC with 2x LDCs
GDC event header
LDC event header
Equipment header
Event Fragment
Equipment header
Event Fragment
LDC event header
Equipment header
Event Fragment
“pointers” Offline recommends to record data with GDC format
even if there is only 1 LDC !
DATE V5 9Data Format
Format Selection in DAQ
Switch on event-building in order to have data formatted with GDC format
Switch on recording on PDS in order to start the recording program in ROOT format.
DATE V5 10Data Format
Format Selection in ECS
Switch on event-building in order to have data formatted with GDC format
Switch on recording on PDS in order to start the recording program in ROOT format.
DATE V5 11Data Format
Conclusion
Everything is crystal clear !
References:
- “Data Format over the ALICE DDL”, ALICE-INT-2002-010 V10.0 - ALICE DAQ and ECS User’s Guide, ALICE-INT-2005-015- Identification of DDL links in ALICE data, ALICE-INT-2006-???